1. Field of the Invention
The present invention relates to adjustable ignition rotors and, more particularly, to an adjustable interlocking ignition rotor utilized in a distributor assembly for setting the timing of an automobile or motorcycle engine.
2. Background of the Prior Art
An internal combustion engine requires quick, accurate and adjustable timing for the firing of the combustible mixture in a piston chamber to obtain maximum power and performance from an engine irrespective of the engine being used for automobiles or motorcycles. The timing is set by a distributor assembly or triggering devices such as pick-up coils to fire spark plugs at different time intervals when the piston stroke provides optimum efficiency and power. An adjustable ignition rotor is a rotating component in the distributor assembly that allows engine timing to be slightly varied to optimize engine power at predetermined engine revolutions per minute (R.P.M.). When utilized to optimize engine power in motor vehicles that do not use distributor assemblies such as motorcycles, the rotor is secured to a rotating crankshaft via a locking key that is integrally mounted to one end of the crankshaft.
Engine timing is set by advancing or retarding (rotating clockwise or counterclockwise) the rotor setpoint from a zero degree position to one or more degrees from the zero degrees setting in either direction. The typical rotor consists of a lower portion that engages a distributor shaft, the lower portion including a zero degree mark scribed thereon, an upper portion having a plurality of timing adjusting marks scribed thereon corresponding to increments of engine timing, central orifices through both upper and lower portions to allow a distributor shaft to pass therethrough, and arcuate adjustment slots oppositley positioned in the upper portions of the rotor. The slots removably receive setscrews that are ultimately secured to the lower portion. The slots are dimensioned to allow the upper portion to rotate (the setscrews being inserted through the slots, loosened, and secured to the lower portion) sufficiently to position any of the scribed marks on the upper portion adjacent to the zero scribe mark on the lower portion thereby selecting engine timing to an advanced or retarded setting.
FIGS. 1-5 illustrate a typical prior art device with FIG. 1 depicting a exploded top, right perspective view, FIG. 2 depicting an exploded bottom, right perspective view, FIG. 3 depicting an exploded top, left perspective view, FIG. 4 depicting a bottom view of the lower portion and FIG. 5 depicting a bottom view of the upper portion.
One problem with the prior art device is that the setscrews tend to loosen over time due to engine vibrations thereby allowing engine timing to vary from optimum performance. Another problem is that a paralax phenomenon is generated. More Specifically, the scribed marks used to align the upper and lower portions can be very difficult to align due to small, tight marks and varying angles of view a person might have when adjusting the marks on the rotor while the rotor is joined with the distributor shaft or when the rotor is joined to one end of a crankshaft.. Another problem is that it is very difficult to maintain the position of aligned scribe marks while tightening the setscrews. Still another problem is that the setscrews have a tendency to come completely out of the threaded orifice in the lower portion, then fall into the engine or distributor assembly and become difficult to retrieve. Yet another problem with prior art rotors is that they are time consuming to adjust due to the very small rotation distances a mechanic must cope with when varying engine timing by as little as one degree or less.
A need exists in the art for a device that reduces time for setting engine timing. Also a need exists for maintaining the setting of an engine's timing, preventing the loss of setscrews while adjusting engine timing, and increasing accuracy and consistency when aligning scribed marks on the upper and lower portions of a rotor device in a distributor assembly or when joined to one end of a crankshaft.